Antti Salonen <[email hidden]> wrote in message news:<[email hidden]>...
Quoted message said:In rec.bicycles.tech John Henderson
Quoted message said:I got to wondering about the cause, and thought that I
might have ridden close to a strong AC magnetic field at
mains frequency. Since the Australian mains frequency is
50 Hertz, this could have switched the fork-mounted
pickup at either 50 or 100 times per second (depending
on whether both half-cycles did the switching, or only
one - an AC electromagnet reverses polarity with each
half-cycle). Given that the computer is configured for a
wheel circumference of 2050 mm, that gives me a
switching frequency of 50 Hertz exactly (to 3 decimal
places) for 369 kph.I also have a VDO computer (wireless) and yesterday I
managed to ride
565.65 km/h. Can you explain this too? The wheel
circumference is 2095 mm.-as
Dear Antti,
I doubt that it's weird Finnish electricity.
It may have been something other than interference, such as
a programming glitch deep in the bowels of the speedometer.
Or the frequency of whatever you rode past might not be 50
Hz. If John's theory is correct and plain Hertz is all
that's involved and that's what happened to your
speedometer, then you need a roughly 76~77 Hz source.
Or you may have ridden past more than one source of radio
interference, hitting a spot where out-of-phase waves
combine to produce a higher overall frequency.
Or your magnet confused things further.
Or you are a superhuman but exceptionally modest rider, in
which case you must let us know what your speedometer reads
when you are leaping over tall building with a single bound.
Carl Fogel